Microtubules are hollow polymers made up of tubulin subunits. Neurons, like other eukaryotic cells, contain a pool of free tubulin subunits and a pool of the microtubule polymers. These two pools dynamically exchange with one another such that microtubules undergo bouts of assembly and disassembly.n neurons, microtubules are also nucleated at the centrosome (located in the cell body of the neuron), but the microtubules are then severed from the centrosome so that they can be deployed into axons and dendrites.
If the parent makes this election, the child does not have to file a return. Earned and Unearned Income. If a child has both earned and unearned income, he or she must file a return (2016 and 2015) if: unearned income was over $1,050; earned income was over $6,300, or
If you are older than 65, you must file if your taxable income is over $11,200. To file as a head of household, you must have at least one dependent and not be married. If you use this filing status, you must file a tax return if you are less then 65 years old and have at least $12,500 in taxable income. If you are older than 65, the threshold increases to $13,950. Married couples can chose to file a joint return or two separate returns.